KMT2D and congenital heart disease: The patient underwent second-generation high-throughput clinical exome sequencing for congenital heart defects seven days after birth, and the sequencing results revealed a heterozygous mutation in the KMT2D gene, NM_003482.3:c.4195C>T(p.Gln1399*), located at position chr12:49441789 (reference GRCh37).